Revision 2605

Various small fixes in doc-strings.
(FileShapeStore): New class.
(ShapefileStore): Derive from FileShapeStore.
(ShapefileStore.__init__): Call __init__ of FileShapeStore,
rename self.table to self._table, initialize self._bbox
(ShapefileStore._open_shapefile): Use self._bbox instead of self.bbox
and self.FileName() instead of self.filename.
(ShapefileStore.Table): Use self._table instead of self.table.
(ShapefileStore.FileName): Removed (moved to FileShapeStore).
(ShapefileStore.BoundingBox):  Use self._bbox instead of self.bbox.